A Computer Simulation of Multi-Ship Encounters

Abstract

In a previous paper a model was outlined for an encounter between two vessels. This paper shows how the model has been developed to include the simulation of the behaviour of more than two ships, the entrance to harbours, and narrow channels.In a previous paper by the authors the concept of a domain was examined. Goodwin's definition of a domain was used, namely, ‘the effective area around a ship which a navigator would like to keep clear with respect to other ships and stationary objects’. The concept of distinct sectors for sidelights and sternlight was modified mathematically so that an area equal to the total of the segments was contained within a circle. By off-centering the position of the ship within this circle, the weighting of the differing areas for the various sectors was retained (Fig. I). A second circle with the ship off-centre was introduced called an arena or ‘sphere of influence’. When a ship is inside the arena a navigator becomes aware of the other ship and decides what action, if any, is needed to keep his own domain unviolated. This resulted in a model which obeyed the Collision Regulations.

A Survey on Ship Collision Risk Evaluation

“…Therefore, Davis and Dove [12] Figure 6. Davis and Dove [13] proposed a concept of Arena, which is used for navigators to determine the time of taking collision avoidance action.…”

Evolutionary approach to ship's trajectory planning within Traffic Separation Schemes

“…A ship domain can be determined on the basis of the ship's length, its motion parameters and type of water region. Since the shape of a domain is dependent on type of water region, the author has decided to use a ship domain model by Davis [5], which updated Goodwin model [7], for open waters and to use a ship domain model by Coldwell [3], which updated Fuji model [6], for restricted waters. The last parameter -the necessary time, is computed on the basis of navigational decision time and the ship's manoeuvring abilities.…”

Ship intelligent autopilot in narrow water

“…It is the value of the 'Time to the Closest Point of Approach (TCPA)' that influences when the selected manoeuvre should be conducted. In order to determine when the first manoeuvre of anti-collision shall be taken, Davis et al used a large version of the domain as his arena [3,5]. It was suggested that the action should be a function of the time taken to the Closest Point of Approach (CPA) of the own-ship.…”